Conventionally, a vehicle axle of a commercial vehicle comprises an axle body which on one side by means of at least one trailing arm forms an axle assembly and therefore is movably hinged on the vehicle frame and supported relative to the vehicle frame by means of a respective air spring arranged above or behind the crossing area of the axle body and the trailing arm. The air spring in turn comprises an air bellows arranged between a cover and a base plate, wherein for a mechanical coupling between the air bellows on the one hand and the axle assembly on the other hand there is provided a plunger piston which is arranged on the air bellows. At its axle-side region the air bellows is connected to the plunger piston, wherein an outer surface of the plunger piston serves as a rolling or unfolding surface for the air bellows so that a guided movement of the air bellows is ensured during operation when the plunger piston moves up and down.
However, such air springs are to a limited extent only suitable for crane and train loading since due to the weight of the axle, which will then hang below the vehicle, the air bellows is completely extended or unfolded without further support devices so that a negative pressure is generated in the air bellows relative to its surroundings. When the vehicle is set down, there is the danger that the air bellows folds towards the inside or tilts relative to the plunger piston or folds in and, hence, does not unroll or unfold along the plunger piston, as would be normal operation, which might lead to damage.
In order to avoid this problem, conventionally in crane and train loading the range of spring of the air spring is limited by means of a tensioning or gripping device attached to the vehicle frame, or a divided plunger piston is used. Alternatively, the air spring may also be designed such that the air spring is releasably connected to the body and, in the case of crane loading of the trailer, the air spring is separated from the body by means of a returning device, and by means of the returning device the cover, and thus the bellows as well, is held in a defined position relative to the plunger piston so that the bellows unrolls or unfolds along the plunger piston or is held in an unrolled or unfolded state.